1. Field of the Invention
This invention concerns a microchip testing device that has a microchip and that analyzes sample liquids by the light intensity analysis method.
2. Description of Related Art
There has been much attention in recent years to analysis methods that use microchips, called μ-TAS or Lab, on a Chip, with equipment that has been made much smaller, by application of semiconductor miniaturization technology and micromachine production technology, than conventional equipment for chemical analysis and so on. When μ-TAS is used in the medical field, it is possible to lighten the burden on patients by reducing the size of blood and other samples, for example, and it is possible to reduce reagent quantities, and thus, reduce analysis costs. Because of the smaller size of the equipment, there is the additional advantage that analysis can be performed simply.
Absorptiometric analysis using microchips measures the concentration of sample enzymes in blood plasma through a series of operations: (1) sample liquid collected with a painless needle is introduced into the microchip; (2) blood plasma and blood cells are separated by centrifugal processing of the sample liquid within the microchip; (3) the blood plasma and a reagent are mixed evenly to become a measurement sample liquid; (4) the measurement sample liquid is introduced into the optical measurement chamber; and (5) light from a light source is irradiated on the measurement sample liquid introduced into the optical measurement chamber and the attenuation of light of specified wavelengths is measured.
In Japanese Pre-Grant Patent Publication 2006-145309 and corresponding U.S. Patent Application Publication 2006/0103848, for example, there is a description of a microchip testing device in which a measurement sample liquid is introduced into the optical measurement chamber of a microchip, light from a light source is irradiated on the optical measurement chamber, attenuation of light of specified wavelengths is measured by a detector, and the concentration of sample enzymes included in the blood plasma is measured.
FIG. 23 is a schematic representation of an example of a conventional microchip testing device used to analyze sample liquids.
This microchip testing device comprises a chip holder 102, a light source 103, and a detector 104, with a microchip 101 in which an optical measurement chamber 105 has been formed that is housed in the chip holder 102. The light source 103 is located in a position from which it can irradiate the optical measurement chamber 105 with light, and the detector 104 is located in a position from which it can receive light that has passed through the optical measurement chamber 105.
Nevertheless, in the conventional microchip testing device shown in Pre-grant Patent Report 2006-145309 and corresponding U.S. Patent Application Publication 2006/0103848, the construction of the chip holder 102 is not described such that its details can be determined. Further, the diameter of a cross section perpendicular to the optical axis of the optical measurement chamber 105 of the microchip 102 is, for example 1.0 mm2, and with the chip simply accommodated without being positioned within the chip holder 102, it is difficult to radiate the beam accurately. When the beam does not irradiate the optical measurement chamber 105 accurately, the light path of the light transiting the optical measurement chamber 105 is extended slightly and attenuation of the light increases; this can cause erroneous analysis results to be output. Therefore, since absorptiometric analysis requires exact positioning of the microchip 101, it cannot be performed with a microchip 101 that is simply accommodated in the chip holder 102.
Further, there is the possibility that the sample liquid will run over when it is injected into the microchip 101. If the spilled sample liquid adheres to the chip holder 102, it can influence the results from examination of another microchip 101. From the hygienic aspect as well, it is preferable to be able to remove the spilled sample liquid.